Building Confidence in Variety Testing

Variety testing performance guides are now available at Outreach and Extension Centers and it is
worth every crop farmers time to look over the yield data. These are some of the
best sources for selecting varieties for next year.

Most agricultural experiments such as the variety trials
will have Least Significant Differences (LSD's) listed in the tables. LSD's can
greatly benefit your decision making ability if you understand how they work.

Let's say you step off 1/100th of an acre of each of
three corn rows in a field and measure the yield in each row. Yield differences are
expected to occur between rows. For example: one row will yield 130 bushels per acre, the
second 135 and the third 138. It may be that when you average the entire field it yields
115 bushels. Variations can result from soil type, poor drainage, weed infestation,
fertility, planting depth or a host of other things. LSD helps to remove the normal
variations in an experiment and enhances unbiased results of field treatments.

A common phrase in performance guides is "LSD at the
5% confidence level". This is simply another way of saying there are 95 chances in
100 that this yield variation was due to a variety difference and there are 5 chances in
100 that this was due to unidentified factors.

If the top yielding soybean variety in a test is 50 bushels
and the LSD at 5% equals 5 bushels, you can be 95% confident that varieties yielding 44
bushels or less were lower because of variety, not field variations. Top yielding
varieties inside the LSD are the ones that deserve the most attention.

Side-by-side strip trials are very common when comparing
varieties on farms. The drawback is that they don't accurately account for field
variations unless a check variety is used. A check is simply a single variety planted in
between each variety in the test or sometimes between every other variety in the test.
Final yield results are adjusted across a field based on the variation in the check
strips.

Strip trials have a major place in on-farm testing but
consider their limitations before putting a great amount of stock in their results. Some
seed companies put a lot of stock in strip trials with no replications or checks, but
their confidence comes from having many locations to compare. The fewer strip trials there
are, the greater the importance of having checks to remove field variability.

Variation is normal, so look for the LSD and the confidence
level in small plot tests or the presence of checks within strip trials when you are
comparing a new product or farming practice. These will give you greater confidence in
variety selection.

Rotating Herbicides -- More Than a Name Change

Pesticide resistance was
first detected with insect control. An early example was when the insecticide DDT become
ineffective against several insects - most notably the housefly. Later, when synthetic
pyrethroid insecticides were introduced it was expected that they would not have
resistance problems for a long time since they were a different chemistry. Resistance
began appearing relatively soon after pyrethroids were introduced. The reason was
discovered to be that the mode of action was the same as DDT even though they were very
different chemistries.

The same thing happens with herbicides. If the mode or site
of action within the weed is the same, then resistance has a chance to build up more
rapidly than with herbicides that attack different sites or have different modes of
action.

The most common herbicide class involved with weed
resistance is commonly known as ALS inhibitors. ALS inhibitors block the amino acid
production of acetolactate synthase (ALS). Therefore, plant growth and development are
stopped and the plant dies.

The ALS inhibitors come from the chemical groups,
imidazolinones, sulfonylureas and sulfonamides. Using different products under these
chemical groups is like using the same herbicide.

cides in the sulfonamides group are Broadstrike, Hornet, and Scorpion III (flumetsulam), and FirstRate
(cloransulam). New products, mixtures, and formulations of ALS inhibitors continue to be
introduced.

Since there are so many different products with the same
mode of action, it is easy to repeatedly use ALS herbicides year after year. Farmers
should rotate between herbicides based on modes of action rather than brand names. Choose
herbicides that are not from the above list, a true herbicide rotation, to avoid weed
resistance. As new products enter the market, be sure to identify mode of action.

Other herbicide modes of action include:

ACCace inhibitors

EPSP inhibitors

Glutamine synthetase inhibitors

Shoot inhibitors

Meristem inhibitors

Seedling growth inhibitors

Pigment inhibitors

Photosynthesis inhibitors

Growth regulators and cell membrane disrupters

Source of modes of action, classes of herbicides, and
herbicide names is from the Ohio Field Crops Weed Control Guide.

We may be inadvertently developing weed resistance by
using the same herbicide year after year. Repeated plantings of Roundup-Ready soybeans and
corn are recent examples of how this can occur. This year waterhemp tolerant to typical
rates of Roundup (glyphosate) were detected in northeastern Missouri. This is the first
sign that resistance is developing rapidly. Also, Touchdown (sulfosate) inhibits EPSP
synthase just like Roundup. Switching between Roundup to Touchdown is not rotating
herbicides. Even though tolerance to Roundup is not wide spread, it should be taken as a
warning. Rotate herbicides voluntarily before it becomes a necessity.

Taxation Tidbits

Long-Term Care Insurance -- Deductibility

Longer life expectancies and escalation of medical and
health care expenses have increased interest in long-term care insurance. The
deductibility of long-term care insurance premiums can substantially influence the
decision to purchase this type of insurance.

For farmers and other self-employed taxpayers, the premiums
for a qualified long-term care insurance contract for yourself, your spouse, or your
dependents are to be included (subject to the limits listed below) in the "health
insurance deduction of the self-employed". The current deductible percentage
(1999-2001) for self-employed health insurance is 60%. The deductible percentage increases
to 70% for tax years beginning in 2002 and to 100% after 2002.

Limits on the annual deduction for long-term care insurance
premiums are the lesser of:

Electronic Crop Trail Results

The University of Missouri Crop Performance Testing (Variety Trial)
results are on the MU Ag Electronic Bulletin Board at:
http://agebb.missouri.edu/

Once at the site go to "Crop Performance
Testing". Data is online for corn, soybean, grain sorghum, hard red winter wheat,
soft red winter wheat and dry bean varieties. To reach the actual data, click on the crop
of your choice, then another screen will appear giving you options on how to view the
data.

Be sure the data represents the most current year.
Information is updated upon completion of harvest and analysis of the data. Once the data
is on the website, it stays until the next harvest. Typically, the data on the website is
the first information available. The written reports are available about a week after the
website is updated.

Although yield usually receives first consideration, other
agronomic characteristics may be equally important when selecting a crop variety or
hybrid.

Soybean Variety Selection
Standability, maturity, herbicide tolerance and
disease resistance are among the characteristics that deserve careful consideration.
Several diseases prevalent in Missouri can be devastating to susceptible varieties.
Lodging may reduce yields and slow harvest. Poor seed quality is often associated with
varieties which mature while temperatures are still high. Late maturing varieties are
occasionally killed by frost. Selection of varieties from several maturity groups can be
helpful in spreading out harvest dates. Increasingly, tolerance to specific herbicides is
important. Therefore, information presented on disease reaction, lodging, herbicide
tolerance, and maturity should also be considered when selecting a variety.

Corn Hybrid Selection
Characteristics that deserve careful consideration
for selecting corn hybrids are: stalk strength, maturity and resistance to insects and
diseases. Later maturing hybrids may require more drying. The maturity classification
listed for each hybrid in this bulletin is based solely on information supplied by the
entry's sponsor. A hybrid with an abnormally low or high moisture content within a
maturity group may be incorrectly classified for Missouri conditions. Poor stalk strength
and/or susceptibility to pests may decrease harvestable yield because of lodging or stand
loss.

Weather Resources on the Internet

At a recent commercial agriculture meeting, Pat Guianan, UMC
Department of Atmospheric Science, presented information on weather resources on the
Internet. There is not room here for all the sites, but here are some weather sites you
might find useful:

Missouri Weather Information on AgEbb:
This site contains information on Missouri weather forecasts, national outlook, river
stage forecasts, monthly weather summaries, and Missouri weather stations across the
state.

Storm Event Data Base:
All notable and severe weather events from 1993 to present including tornadoes,
thunderstorms, and hail. This could be useful in negotiation with insurance companies on
losses due to the weather.

Ag Connection is published monthly for Central Missouri Region producers and is supported by University of Missouri Extension, the Commercial Agriculture program, the Missouri Agricultural Experiment Station and the MU College of Agriculture, Food and Natural Resources. Managing Editor: Kent Shannon.